ISOLATION-TYPE FLYBACK CONVERTER FOR LIGHT EMITTING DIODE DRIVER

摘要

PURPOSE: An insulation type flyback converting circuit for an LED driving device is provided to stably control the second side current of a transformer only with the control of the first side of the transformer without an additional circuit at the second side of the transformer by controlling LED driving without being affected by the variation of an LED load or the variation of the amount of power voltage without an insulation element including a current sensor or an opto-coupler at an insulation type LED driving circuit before improving the power factor of the LED driving circuit. CONSTITUTION: A flyback converting circuit comprises a snubber circuit(300), which is connected to power voltage, for preventing overvoltage or overcurrent, a switching part(200) for switching on and off, and a control part(100). The control part detects a first input signal which is proportional to the variation of the power voltage and a second input signal which is proportional to the envelope voltage of output voltage when the switching part is off. The control part regularly maintains current by controlling the peak current of the switching part for generating a signal which is inverse proportional to the maximum value of the first input signal and controlling the signal to be proportional to the result of the signal multiplied with the second input signal. [Reference numerals] (102) Boundary mode timing generator; (108) Peak voltage detector